672 research outputs found
Suppression of Forward Pion Correlations in d+Au Interactions at STAR
During the 2008 run RHIC provided high luminosity in both p+p and d+Au
collisions at . Electromagnetic calorimeter acceptance in
STAR was enhanced by the new Forward Meson Spectrometer (FMS), and is now
almost contiguous from over the full azimuth. This large acceptance
provides sensitivity to the gluon density in the nucleus down to . Measurements of the azimuthal correlation between a forward
and an associated particle at large rapidity are sensitive to the low- gluon
density. Data exhibit the qualitative features expected from gluon saturation.
A comparison to calculations using the Color Glass Condensate (CGC) model is
presented.Comment: 4 pages, 6 figures, proceeding for the 45th Rencontres de Moriond
(QCD
Two Particle Correlations at Forward Rapidity in STAR
During the 2008 run RHIC provided high luminosity in both p+p and d+Au
collisions at GeV. Electromagnetic calorimeter acceptance
in STAR was enhanced by the new Forward Meson Spectrometer (FMS), and is now
almost contiguous from over the full azimuth. This large acceptance
provides sensitivity to the gluon density in the nucleus down to , as expected for parton scattering. Measurements of
the azimuthal correlation between a forward and an associated
particle at large rapidity are sensitive to the low-x gluon density. Data
exhibit the qualitative features expected from gluon saturation. A comparison
to calculations using the Color Glass Condensate (CGC) model is presented.Comment: proceeding for the RBRC workshop: "Saturation, the Color Glass
Condensate and Glasma: What Have we Learned from RHIC?
Two-particle azimuthal correlations at forward rapidity in STAR
During the 2008 run the Relativistic Heavy Ion Collider (RHIC) at the
Brookhaven Nation Laboratiory (BNL), NY, provided high luminosity in both p+p
and d+Au collisions at . Electromagnetic
calorimeter acceptance in STAR was enhanced by the new Forward Meson
Spectrometer (FMS), and is now almost contiguous from -1<\eta\4 over the full
azimuth. This allows measurements of the azimuthal correlation between a
forward neutral pion and a second particle in a very large rapidity range.
Di-hadron azimuthal correlations provide sensitivity to the low longitudinal
momentum fraction () component of the gluon density in the nuclear target.
Initial state nonlinear effects are in fact expected to appear in d+Au
collisions when the dense part of the nucleus is probed. The analysis in this
thesis shows that such correlations and their dependence on rapidity,
transverse momentum and collision centrality are qualitative consistent with
the existence of gluon saturation effects in the relativistic nucleus.
Theoretical expectations for azimuthal correlations between a dilute system
(deuteron) and a saturated target (Gold nucleus) have been explored.Comment: 108 pages, Ph.D. thesi
CGC and initial state effects in Heavy Ion Collisions
A brief review of the phenomenological studies in the field of heavy ion
collisions based on the Color Glass Condensate theory and, in particular, of
those relying in the use of the BK equation including running coupling effects
is presented.Comment: 6 pages, 5 figures. Contribution to the proceedings of the Hot Quarks
2010 Conference. June 21-26, La Londe Les Maures, Franc
Dynamics of in vitro rumen methane production after nitrate addition
The present study aimed to assess the dynamics of rumen methane (CH4) production following the addition of NaNO3. This was done using an in vitro rumen fermentation system that ensures continuous gas and methane assessments. Four different levels of NaNO3 were used to get the final nitrate concentrations of 0.5, 1.0, 1.5, and 2.0 mg/ml of rumen fluid. For each dose, corresponding controls contained sodium chloride and urea were realised to ensure comparable levels of sodium and nitrogen. The addition of nitrates had slight effect on the intensity of fermentation because the total gas produced minus CH4 (total methane-free gas) only went down at the highest dose (2.0 mg/ml), and the final concentrations of SCFA were the same at all doses. The most evident effect was a modification of the SCFA profile (low concentrations of propionate and valerate, progressive increments of acetate, and decreases of butyrate) and a reduction in overall CH4 production. The CH4 yield for the 0.5 mg/ml dose was not different from control in the entire fermentation. Yield of the 1.0 mg/ml dose was significantly lower than the control group (p < 0.05) only within the initial 24-h period, and higher dosages (1.5 and 2.0 mg/ml) were lower during the entire fermentation (p < 0.01). Methane yields were well fitted with the Gompertz model, but only the highest level of nitrate inclusion had a significant impact on the majority of model parameters (p < 0.01). The linear regressions between CH4 yields (y) and the amounts of nitrates (x) at progressive fermentation durations (e.g. 6, 12, 24, and 48 h) produced equations with increasing absolute slopes (from −0.069 to −0.517 ml/mg of nitrate). Therefore, nitrate reduced rumen CH4 yield in a dose-dependent manner: the impact of low doses was primarily observed at the initial stages of fermentation, whereas high doses exhibited effectiveness throughout the entire fermentation process. In conclusion, in batch fermentation systems, the dose effect of nitrates on methane yield was time dependent
Initial and Final State Interaction Effects in Small-x Quark Distributions
We study the initial and final state interaction effects in the transverse
momentum dependent parton distributions in the small- saturation region. In
particular, we discuss the quark distributions in the semi-inclusive deep
inelastic scattering, Drell-Yan lepton pair production and dijet-correlation
processes in collisions. We calculate the quark distributions in the
scalar-QED model and then extend to the color glass condensate formalism in
QCD. The quark distributions are found universal between the DIS and Drell-Yan
processes. On the other hand, the quark distribution from the
channel contribution to the dijet-correlation process is not universal.
However, we find that it can be related to the quark distribution in DIS
process by a convolution with the normalized unintegrated gluon distribution in
the color glass condensate formalism in the large limit.Comment: 20 pages, 6 figure
Caspase-3-like activity and proteasome degradation in grapevine suspension cell cultures undergoing silver-induced programmed cell death
Toxic metal contamination is one of the major environmental concerns of the recent decade, due to the large application of metals in industrial, healthcare and commercial products, even in the form of nanostructures and nanomaterials. Nevertheless, the effects of silver (Ag+) on plants have not yet thoroughly elucidated. Therefore, suspension cell cultures of grapevine were used as a model for investigating silver toxicity. To do this, oxidative
stress and programmed cell death (PCD), evaluated as reactive oxygen species production, caspase-3-like activity and ubiquitin-proteasome system, were investigated.
As a result, the highest concentration (10 \u3bcM) of Ag+ caused a rapid (within 24 h) induction of PCD (approx. 80%), accompanied by generation of reactive oxygen species and activation of caspase-3-like activity. In the presence of specific inhibitor of this enzyme, a partial recovery of cell viability and a strong inhibition of caspase-
3-like activity was observed. In addition, silver-induced PCD was accompanied either by increase of poly-ubiquitin conjugated proteins and degradation of subunit PBA1 of the proteasome 20S core, similarly to what found for metal-induced neurotoxicity in animals.
The present study shows that silver could induce PCD in grapevine suspension cell cultures, mediated by caspase-3-like activity and oxidative stress. These effects were associated to accumulation of poly-ubiquitin conjugated proteins, suggesting the impairment of ubiquitin-proteasome complex, confirmed by the decrease of the PBA1 subunit. These findings indicate that animal and plant cells could share a common pathway in response
to toxic metal, which involves PCD and disassembling of proteasome complex
Tools for Nano-Enabled Agriculture: Fertilizers Based on Calcium Phosphate, Silicon, and Chitosan Nanostructures
The Green New Deal requires a profound transformation of the agricultural sector, which will have to become more sustainable and ensure universal access to healthy food. Thus, it will be essential to introduce radical technological innovations. Nanotechnologies have the potential to produce a significant boost to the improvement of the food system. Within this context, in the
next years, a strong challenge will need to be faced regarding developing new and more efficient uses of nutrients in agriculture, being the nutrient use efficiency (NUE) paramount in sustaining
high crop productivity without depleting biodiversity, and altering both the natural and agricultural systems. Nutrients leaching causes environmental pollution and water eutrophication, while nutrient excess favors pest and weed widespread. Therefore, it will be mandatory to improve plant nutrition efficiency without affecting agricultural productivity and economic sustainability. A promising alternative consists of the introduction of the so-called nanomaterial enhanced fertilizers and plant growth stimulators. Such innovation includes nanotechnological solutions that can improve nutrient delivery for a more finely tuned, accurate, and saving-resources distribution of nutrients. This review provides a critical view of the latest advances in nanofertilizer research, mainly referring to nano-hydroxyapatite, silica nanoparticles, and chitosan-derived nanostructures
Looking forward for Color Glass Condensate signatures
Forward production has been measured at STAR with the new Forward
Meson Spectrometer (FMS) from p+p and d+Au collisions during the 2008 RHIC run.
We present the first FMS results of azimuthal correlation involving a forward
produced in p+p and d+Au collisions to search for the onset of gluon
density saturation, expected to occur at small momentum fractions.Comment: 4 pages, 4 figures, - to appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse
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